Study On Root Characteristics Of The Population Of Recombinant Inbred Lines Derived From Zhenshan 97/Minghui 63 And Their Effect On Grain Yield

In order to illustrate the root characteristics of high-yielding rice and to provide further experimental base for the genetic improvement of rice root traits, the population of recombinant inbred lines (RILs, F12. F13) derived from Zhenshan 97 / Minghui 63, parents of Shanyou 63,an elite Indica hybrid in China, was solution-cultured and the relationship between yield formation and root morphological and physiological traits was systematically analyzed. Results showed as follows:(1) Seed setting percentage of high-yielding rice was higher and steady. The number of panicles per unit of area, the number of spikelets per panicle and 1000-grain-weight in high-yielding rice were also higher than that in lower-yielding rice but the range of these three yield components in high-yielding rice is large.(2)Biomass production in the entire growth period, dry matter accumulated before and after heading stage, economic coefficient in high-yield rice were higher and their deviations were relatively narrow.(3) High-yielding rice, had more adventitious roots per plant and higher root dry weight at heading stage. Total length of adventitious roots per plant and length of the longest adventitious root were longer in high-yielding rice. Higher total root activity and larger total and active absorption area of root per plant were also observed in high-yielding rice.(4) RILs with larger sink had more panicles per unit area, larger panicle and more spikelets per unit area. 1000-grain-weight were relatively high and steady in RILs with large sink.(5) Biomass production, dry matter accumulated before or after heading stage were higher and steady in Indica rice with large sink.(6) Root characteristics of Indica rice with large sink were as follows:more adventitious root per plant, higher root dry weight per plant or per adventitious root, longer length of adventitious root per plant and the longest adventitious root, longer mode root length, and higher coefficient of variation (CV) of the above-mentioned root traits. Indica rice with large sink also had higher root activity per plant, larger root absorption or active absorption area.(7) Main root characters which significantly affected grain yield in RIL population were: root activity per plant, root activity per spikelet, root dry weight per plant, length of the longest adventitious root, length of mode roots, length and width of single adventitious root, among which root activity per plant had most significant effect on grain yield. Raising root activity per plant, root dry weight per plant, length of the longest adventitious root, and width of single adventitious root resulted in significant increase of grain yield in RILs, while increase in root activity per spikelet, length of single adventitious root and length of mode roots could lead to obvious decrease of grain yield in this population.(8) Grain yield of high-yielding lines in RIL population could be enhanced by raising root dry weight per plant, dry weight per adventitious root, root dry weight per unit length, and root activity per plant. Raising root activity per spikelet could significantly increase grain yield of high-yielding lines in RIL population. Root dry weight per plant had positive correlation with grain yield of high-yielding lines, while number of adventitious roots per plant had the same important effect on low-yielding lines.(9) Increasing number of adventitious roots per plant, root dry weight per plant, total length of adventitious roots per plant, root weight per unit length, root activity per plant, and root activity per spikelet could significantly increase grain yield in lines with larger sink (in cluster A and B), while grain yield in lines with smaller sink (in cluster D and E) was slightly correlated with root weight per unit length.